The present invention relates to battery chargers and more particularly to battery chargers adapted for automatic unattended operation.
Modern technology has made portable apparatus containing rechargable battery power supplies common place. Everything from electric drill motors to intercommunication systems are available for portable use without the limitations attendant to the necessity for attachment to a local source of power. Such apparatus has found particular widespread acceptance among emergency organizations such as fire fighters and police. When being used by such organizations, however, portable rechargable battery powered equipment must be constantly at its peak of operational potential. Unlike the casual user, a fire fighter using a portable communications device at the site of an active fire cannot stop to recharge batteries which were inadvertently left in an uncharged condition.
The transportation equipment employed by such organizations typically is outfitted with heavy-duty batteries capable of recharging the small rechargable batteries employed in such portable apparatus. While at the home station, a conventional source of A.C. power is usually available. In the case of a major disaster, however, even such normally available A.C. power may be unavailable for long periods of time. Nevertheless, the radios and the like require recharging after extended periods of use and maintenance at peak operating potential during periods of non-use.
Such organizations typically have a multiplicity of substantially identical units having identical recharging needs. That is, for example, perhaps 6 or 8 hand-held or hat-mounted radio receivers readily adapted for simultaneous recharging. Thus, a battery charger capable of simultaneously recharging a group of such radios simultaneously from whatever power source is immediately available (be it D.C. from the large capacity battery of a fire truck or A.C. from the wall outlet at a fire station) would be highly desirable. Such a battery charger should ideally be adapted to prevent interaction between power sources should the charger be simultaneously connected to both an A.C. source and a D.C. source. Moreover, such a charger should prevent interaction between batteries being simultaneously charged, include voltage regulator means for setting the maximum voltage being charged to, as well as controlling the charging rate to all the batteries in unison, and include means for individually controlling the charging rate to separate batteries as each battery attains its maximum charge level.
Wherefore, it is the object of the present invention to provide a battery charger having the aforementioned attributes as well as other desirable features which will become apparent from reading the description thereof, which follows hereinafter.